1. Technical Field
The invention relates to a process for storing a refined liquid hydrocarbon product and more particularly to a process for storing a refined liquid hydrocarbon product in a tank.
2. Background Information
Liquid hydrocarbon product from a refinery is typically distributed to regional terminals for storage and distribution to local markets. Large above-ground storage tanks are the most common means for storing product at the terminals.
Above-ground storage tanks usually have an outlet port in their sidewall to enable withdrawal of liquid product from the tank. However, the position of the outlet port can create a dead volume in the internal tank volume extending from the level of the port down to the bottom of the tank. Although this dead volume can beneficially accumulate contaminants which settle to the bottom of the tank, such as water, the dead volume can also contain useful product. The product in the dead volume is effectively unusable because it is difficult to recover. As a result, the tank operator incurs high inventory carrying costs.
The only practical means for recovering the product accumulated in the dead volume is to slowly pump it out through specially connected auxiliary pumping equipment. Nevertheless, even this procedure is operationally difficult. For this reason, the product occupying the dead volume is usually left in place when emptying the tank of stored product.
A need exists for a process of storing a refined liquid hydrocarbon product in a storage tank which effectively utilizes the entire tank storage volume without losing product to tank dead volume. A need further exists for a process of storing a refined liquid hydrocarbon product in a storage tank which enables one to store the product in the tank or withdraw the stored product from the tank without contamination of the product.